The present invention relates generally to the field of non-destructive testing and, in particular, to a new and useful method for testing boiler and furnace header tube stubs using electromagnetic acoustic transducer (EMAT) technology.
Latimer et al. (U.S. Pat. No. 5,035,143) discloses a method for ultrasonically detecting creep swelling in tubular members such as fossil utility steam lines and headers. Either standard piezoelectric transducers or EMATs can be used to generate the ultrasonic waves.
Ultrasonic inspection of header tube stubs, among other locations in an industrial furnace or boiler, is difficult using conventional ultrasound techniques. Conventional ultrasound techniques using piezoelectric transducers require a critical alignment of the transducer with the object under test. Adequate couplant must be maintained between the ultrasonic transducer and the object, and access is limited in many areas where the operator may be reaching through several tube banks. In addition, a conventional ultrasonic inspection using a piezoelectric transducer must scan completely around the tube stub, a task which is sometimes virtally impossible considering the problems of access, alignment, and maintaining adequate couplant. For these reasons, there is presently no known method for conducting a complete ultrasound technology assessment of boiler and furnace tube stubs and headers.